In general, any mouse that normally lives in fields; more strictly, any of about seven species of small, long-tailed mice in the genus Apodemus (family Muridae). Field mice in this genus are found in fields, woodlands, and mountain meadows in the warm and temperate parts of Eurasia. They are grayish or light or reddish brown and are 2–5 in. (6–12 cm) long excluding the tail. They generally live in burrows and build nests of grass and other plants. They eat seeds, roots, and other plant material, occasionally damaging crops or young trees.